T–63
SECTION 17 STANDARDS APPLICABLE TO PULLEYS AND FLANGES
Pulleys are components manufactured to close tolerances in order to achieve best performance
and long belt life. They are available in finished form or as bar stock which can be used for in-house
manufacture of prototypes or smaller quantities.
For an uninitiated observer, a pulley may appear simply as a component with some trapezoidal
or curvilinear grooves. In fact, the efficiency and integrity of a belt drive is closely attributed to the
quality of pulleys involved. The pulleys, therefore, should be supplied by qualified and licensed
suppliers. In case of HTD and GT drives, the suppliers must be licensed by the Gates Rubber
Company. Stock Drive Products is one of such licensed full line suppliers.
To achieve the reproduction of the correct pulley profile, licensed hobs are used. The following
inspection and design aids are used as well:
Master Profile: A scaled line drawing of the ideal groove profile with tolerance bands plotted
on dimensionally stable translucent material. Suitable for groove inspection purposes on an optical
comparator.
Dimensional Profile Drawing: A line drawing of the ideal groove profile with all arcs and radii
defined. Suitable for mold design.
Digitized Points: A series of X and Y coordinates defining the ideal groove profile. Available
in printed form or on a floppy disk. Suitable for mold design.
Table 25 Center Distance Tolerances
inches
mm
inches
Center Distance
Tolerance
Belt Length
Up to 10
Over 10
To
15
Over 15
To
20
Over 20
To
30
Over 30
To
40
Over 40
To
50
Over 50
To
60
Over 60
To
70
Over 70
To
80
Over 80
To
90
Over 90
To
100
Over 100
To
110
Over 110
To
120
Up to 254
Over 254
To
381
Over 381
To
508
Over 508
To
762
Over 762
To
1016
Over 1016
To
1270
Over 1270
To
1524
Over 1524
To
1778
Over 1778
To
2032
Over 2032
To
2286
Over 2286
To
2540
Over 2540
To
2794
Over 2794
To
3048
±.008
±.009
±.010
±.012
±.013
±.015
±.016
±.017
±.018
±.019
±.020
±.021
±.022
mm
±.20
±.23
±.25
±.30
±.33
±.38
±.41
±.43
±.46
±.48
±.51
±.53
±.56
Table 26 Overall Belt Thickness Dimensions
inches
mm
Overall Thickness
(ref.)
Belt Type
Belt Pitch
MXL
40 D.P.
XL
3 mm HTD
5 mm HTD
2 mm GT
3 mm GT
5 mm GT
T2.5
T5
T10
.080"
.0816"
.200"
3 mm
5 mm
2 mm
3 mm
5 mm
2.5 mm
5 mm
10 mm
.045
.045
.090
.095
.150
.060
.095
.150
.051
.087
.177
1.14
1.14
2.29
2.41
3.81
1.52
2.41
3.81
1.3
2.2
4.5
Table 27 Overall Belt Thickness Tolerances
Standard
Class 2
Class 1
±0.015"
±0.38 mm
±0.010"
±0.25 mm
±0.005"
±0.13 mm
NOTE 1:
Belts with pitch lengths greater than 5.5"
(140 mm) are furnished with a Class 2
grind unless otherwise specified. Belts
with pitch lengths less than 5.5" (140
mm) are unground and produced to
standard tolerances.
NOTE 2:
A Class 1 grind is available at additional
cost for finished belts only.
